“Using a data set for all sumo wrestlers in the post-World War II period, this paper investigates how wrestlers’ body mass index (BMI) is associated with their win rate and absence rate. Further, the effect of BMI is compared between an early period (before the emergence of foreign wrestlers) and later period (after the emergence of foreign wrestlers). After accounting for endogenous bias using instrumental variables, the key findings are that (1) there is no positive relationship between the BMI and win rate in either the early or later period and (2) there is a positive relationship between the BMI and absence rate in the later period but not in the early period. From the findings in this paper, I make the argument that an increase in the number of immigrants with human capital different from that of domestic labor leads the domestic labor to obtain human capital that does not match its characteristics, thereby reducing its performance.”
Here’s detail from the study:
(Thanks to Hiroshi Gunji for bringing this to our attention.)
Medical researchers, seeking insight, sometimes try to make simple sense of complex, difficult conglomerations of things that may or may not have effects on each other and on many other things. Sometimes coffee is involved, as is the case here:
“The aim of this study was to investigate the association of HRV [heart rate variability] indices with indoor air pollution, working time and coffee consumption…. We recruited 60 young healthy convenient store workers to monitor indoor PM2.5 (particulate matter with an aerodynamic diameter ≤ 2.5 µm) exposures, coffee consumption (yes vs. no) and HRV indices during daytime (0700-1500 hours) and nighttime (2300-0700 hours)….
“CONCLUSIONS: …The effect of indoor PM2.5 on HRV indices may be modified by coffee consumption in young healthy convenient store workers.”
A good number of people would probably find walking across a tightrope or slackline a decidedly non-trivial task. If it helps, assistance is at hand in the form of a comprehensive mathematical analysis which looks not only at the effect of the human on the rope, but also the rope on the human – in four dimensions.
See: ‘Balancing on tightropes and slacklines’ Journal of the Royal Society, Interface (2012) 9, 2097–2108. A joint investigation by Dr. Paolo. Paoletti (now at Centre for Engineering Dynamics, School of Engineering, University of Liverpool), along with L. Mahadevan (Lola England de Valpine Professor of Applied Mathematics, Professor of Organismic and Evolutionary Biology, and Professor of Physics, at the Department of Organismic and Evolutionary Biology, and Wyss Institute for Bioinspired Engineering, Harvard University, Cambridge US.) [The professor was co-recipient of the 2007 Ig Nobel physics prize for studying how sheets become wrinkled.]
“Our analysis of the open and closed-loop dynamics shows the existence of an optimal rope sag where balancing requires minimal effort, consistent with qualitative observations and suggestive of strategies for optimizing balancing performance while standing and walking.”
Improbable Clarification : A tightrope is a slackline that’s too tight, and a slackline is a tightrope that’s gone loose.
Last night, we went to a screening of “Who Framed Roger Rabbit?” The movie was preceded by a talk by Melissa Franklin, chair of the Harvard Physics department and one of the discoverers of the Higgs boson. Dr. Franklin talked for about 20 minutes on the physics of cartoons, and the role of cartooning in physics. She was as funny as a professional comedian. She’s like Ellen Degeneres with an IQ of two thousand.
You just don’t GET that kind of entertainment in every city, folks.
Here’s a scene from the movie:
BONUS: Mark O’Donnell’s list, originally published in Esquire magazine, of “The Cartoon Laws of Physics“. In her talk, Professor Franklin lauded the robust subtleties of these laws.